Spatially resolving biomolecules in two dimensions on a substrate is an important tool in molecular biology. Components of complex mixtures of biomolecules can be spatially resolved on a gel or blot and imaged or scanned to measure levels of specific biomolecules of interest. Likewise, biomolecules may be bound to an array, or spatially segregated in wells of a microtiter plate and may again be measured by imaging or scanning. Different methods of labeling biomolecules require different measurement techniques to read out the analysis.
One method of imaging fluorescent molecules is to use an optical scan head, where an objective lens is linked to a light source and detectors through a series of beam splitters and filters designed to enable detection of a certain fluorophore or phosphor. This directs light of a particular wavelength range to excite a fluorophore or phosphor, and directs the emitted light selectively through to a detector. This scan head may be moved along the 2-dimensional axes of the substrate in order to get a high-resolution readout of fluorescence for the entire substrate. Or in some cases, the substrate may be moved in 2-dimensions in front of the objective.
It is not unusual to combine fluorescent and phosphorescent detection into a single device. Having a dedicated instrument for each technique can be expensive to acquire and maintain, and will take up precious space in a laboratory. Having multiple readouts creates a flexible instrument, also allows interrogation of multiple biomolecules simultaneously. However, enabling the detection of multiple “colors” of fluorescence and phosphor can increase the number of scanning heads, adding complexity and cost to the instrument, and can lead to reduced sensitivity if there is overlap between the excitation and emission wavelengths of 2 fluorophores measured with the same optical scan head.
Scanning often involves placing a substrate on a scanning bed that is considerably larger than the substrate. Scanning the entire scan bed results in wasted time and data storage for the scanning of the region surrounding the substrate.
A need therefore continues to exist for improved biological substrate analyzers and methods of analyzing biological substrates. The present disclosure meets this need.